Coating press and holiday detector



Nov. 6, 195] A. L. SMITH 2,573,815

COATING PRESS AND HOLIDAY DETECTOR Filed May '7, 1946 2 SHEETS-SHEET l l5 2 0 2 IIIIIIII IIIIII IIIIIIIIII.

az F1555 2'5 ALONZO 1.. SMITH- a, [N V EN TOR.

ATTORNE ir'S Nov. 6, 1951 ALSWTH" 2,573,815

COATING PRESS AND HOLIDAY DETECTOR I Filed May 7, 1946 2 SHEETS-SHEET 2 HI] H" In! ALONZO 1.. SMITH INVENTOR.

BY fizz/6M Patented Nov. 6, 1 951 COATING PRESS AND HOLIDAY DETECTOR Alonzo L. Smith, Houston, Tex.

Application May 7, 1946, Serial No. 667,983

2 Claims.

This invention relates to a method and apparatus for the smoothing of pipe wrapping as it is applied so as to uniformly distribute the coating material and to eliminate bubbles and wrinkles, and to fill and detect holidays.

Pipe lines, whether imbedded 'in the soil or supported in exposed position, are commonly covered with a hot coal tar or asphalt coating and then wrapped with a wrapping material such as felt, fabric, and the like, impregnated with a moisture resistant material such as bitumen. The asphalt or coal tar coating and the impregnant are air hardenable within a limited time after being supplied. Such a coating is applied for purposes of excluding moisture to seal the wrapping material and also to act as an insulator and thus prevent the flow of electrolytic or other electric currents, all of which effect rapid deterioration of the pipe line. The coating is commonly applied progressively to the pipe with sufficient heat that it is in liquid form and relatively soft so as to readily conform with and adheres to the periphery of the pipe. However, frequently the wrapping does not adhere closely to the pipe or may be wrinkled and pin holes, bubbles, or other holidays or voids remain as the coating is applied, and the effectiveness of the coating is greatly impaired.

In the past, repair of the holes or holidays in the coating has been effected after the coating hardens by first detecting the flaws and then performing a patching operation as by removing a section of the coating and replacing such section with a patch in which no flaws exist, or by placing additional coating material over the area containing the flaw. Such procedure is unsatisfactory because of consumption of time and cost of material, and also because of difliculty in obtaining a repair that is satisfactory either from the standpoint of effectiveness or appearance. l

The present invention provides a means and method of ironing or smoothing the wrapping while the coating thereunder is still pliable so as to obtain a more uniform distribution of the coating and to remove bubbles and wrinkles and to fill many of the holidays with coating material.

The present invention also comprehends detection of holidays before the coating has hardened by testing the dielectric strength of the coating and, following such detection, by remedial steps to eliminate the holidays'so that there results an impervious and homogeneous coating when the coating material has hardened.

To obtain desired results it is preferable that the mechanism, and the'operative steps of the method, be carried out directly behind the coating and wrapping machine while the coating is still relatively soft so that elimination of bubbles, ironing of the coating and the detection of voids of any kind in the coating can be eliminated prior to the final hardening of the coating.

Another object of the invention is to provide an apparatus and a technique whereby kneading pressure is applied to the surface of the freshly applied coating to smooth the coating and cause bubbles or other sources of holidays to be eliminated.

Another object is to utilize a' circularly arranged spring or resilient member upon the outside of the wrapping which also applies'pressure to the coating so that passage over the wrapping eflects kneading action which smooths the coating and dissipates many of the holidays fromwithin the coating.

An object of the invention is to provide simple and efficient means and method for detecting holidaysin a coating and for applying pressure to the coating at such time that the holidays are eliminated.

The invention also comprehends the application of an electrical potential between the exterior and the interior of a coating to detect holidays in the coating from the flow of an electric current through such holidays.

More specifically, an object is to provide a spring type of electrode in combination with a spring type pressure member which is positioned about the pipe whereby both potential and pressure are applied progressively to the periphery of the wrapping as such combined member is moved along the wrapping.

Another object is to provide a lubricant containing material within the spring which contacts the wrapping so that the soft coating material will not adhere to such spring.

Still another object is to provide an actuator including a yoke or bracket having a sliding connection with the electrode, there being an insulating handle to which the yoke is attached so that the actuator is manually operable to move the electrode and pressure member along the surface of the coating.

Another object is to provide an electrodeand actuating means therefor that can be readily manipulated by the operator to iron the coating and to detect holidays and produce kneading action which removes many of the holidays;

A still'further object is to provide complete 3 equipment that is simple and inexpensive to construct, maintain and operate.

The foregoing objects together with other objects and advantages of the invention will be more fully apparent from the following description considered in connection with the accompanying drawings in which:

Fig. l is an elevational view of the combined electrode and pressure element and the actuator therefor;

Fig. 2'is a detail showing the interconnecting end structures of the electrode;

Fig. 3 is a sectional view taken on the line 33 in Fig. 2;

Fig. 4 is a schematic diagram of an electrical circuit that is used in practicing the invention;

Fig. 5 is an enlarged detail sectional view taken on line 55 in Fig. l;

Fig. 6 is a side View of a spring pressure-ironing or smoothing member used together with an electrode as a unit;

Fig. '7 is a composite view illustrating the pipe having the coating material and the wrapping applied thereto, and illustrating the device of the present invention as closely following these operations.

The invention is practiced where a coating and wrapping is being applied to a pipe such as pipe lines to be buried in the earth. In the drawings the pipe I is first covered with a protective coating of tar, asphalt or the like which has been heated to a liquid state and poured upon the pipe so as to flow down around the pipe with the in tention of covering the entire surface. The wrapping machine usually travelling along upon the pipe then applies a spiral wrapping of felt or fabric while the coating material is still warm or pliable so that the felt will be adhesively attached to the pipe.

In Fig. '7 the pipe I shows the liquid coating material 2 as having been applied b means of a coating apparatus such as 3 which will be pulled along the pipe in a suitable manner with appropriate power machinery not shown.

The wrapping material 4 is then almost immediately applied to the liquid coating 2 while it is still warm and pliable.

It is not at all uncommon to have the wrapping 4 of felt applied with wrinkles in the various layers and to have bubbles or blank spaces in the coating 2 to occur. If there should be small holes or openings in the felt it is possible that holidays in the coating and wrapping may thus occur and even fine pin holes are objectionable because they admit moisture, permit the flow of resident or other electric currents to effect an electrolytic action.

As indicated heretofore the prior practice has been to permit the hardening of the coating material and then efforts conducted todetermine the location of bubbles, holidays or other holes which would be detrimental.

One of the essential features of the present arrangement is the smoothing or ironing or kneading of the wrapping material 4 immediately after its application so as to iron out any bubbles so as to more uniformly distribute the coating material 2 by causing it to flow while it is still soft underneath the layers of wrapping material. This floating of the coating material also serves to fill voids and even small pin holes in the wrapping material so as to eliminate any voids and provide complete insulation for the metal pipe I.

In some instances there are small voids remaining after this ironing operation and in order to detect the presence of such voids by the application of an electric current, the apparatus of Figs. 1 to 5 inclusive has been shown. This apparatus will be used prior to the hardening of the coating material due to the cooling thereof or the drying action.

The invention comprehends the application of an electrical potential between the periphery of the coating 2 and the pipe i encased thereby. To this end there is provided a spring type electrode 5 of which one end has a closure disk 6 having an axial stud 'i' with a head 8 thereon. The other end of the electrode has a closure disk 9 with an eccentric opening In of a size to pass the head 8 so that the neck of the stud 1 may enter the concentric portion ll of the opening in the disk 9 and in this manner the electrode is held in the position shown in Fig. 1.

Inasmuch as the electrode 5 is to be positioned about and rolled upon the coating 2 before the coating has hardened, it is important that steps be taken to prevent adhesion of the coating material to the electrode, and thus to prevent the building up of a mass of the coating material upon the electrode. One manner of accomplishing this purpose is provided by filling the interior of the electrode 5 with a quantity of absorbent material I2. This absorbent material is saturated With a suitable lubricant such as a light gravity oil so that a film of the lubricant Will remain upon the surface of the individual turns of the element 5 and thus prevent adherence of the coating material thereto. It is to be understood that this film of lubricant will not impair the functioning of the electrode as an electrode.

A chain i5 is attached to the eyes [5 and H on the disks 6 and 9. This chain is normally slack and is intended merely to serve as an over-range member by limiting the stretch of the electrode.

The actuator It for the member 5 comprises a handle 2| of insulating material, it bein intended that the actuator shall be manipulated in the hands of the operator without possibility of shock therefrom. A yoke I! of conducting material extends approximatel half way about the pipe I and is attached to one end of the handle. At the outer ends this yoke has arcuate ears I8 which, as best seen in Fig. 5, slidingly fit upon the electrode '50 that movement of the actuator H5 in the directions indicated by the arrows !9 will effect free rolling movement of the electrode upon the surface of the coated tube. One terminal of an electric circuit to be described is attached to the yoke l'i through the conductor 20.

The electrode 5 is energized from any suitable source or circuit, such circuit being shown in Fig. 4 as comprising a generator 25 which is connected through variable resistor 26 to the terminals of the primary 2'! of the transformer 28. A voltmeter 29 across the terminals indicates at all times the voltage applied to the primary of the transformer. One terminal of the transformer secondary 30 is grounded at 3! while the other terminal 32 thereof is connected to a glow tube 33 which is in turn connected to the conductor 20 attached to the actuator iii.

The transformer 28 preferably has a drooping characteristic and for most purposes has an opening circuit terminal voltage in the neighborhood of 30,000 volts, it being understood that different voltages may be used depending upon the condition of the coating material, the nature of such material thickness thereof, etc. In any event, the applied voltage is relatively high and the circuit is therefore referred to as a high tension circuit. This voltage will decrease materially whenever there is a draft of current through the secondary circuit which includes a glow tube 33 and the electrode 5, thence to the pipe I which is normally grounded. The increased flow of secondary current also causes an increased current in the primary circuit of the transformer and hence there is a voltage drop across the resistor 26 and the primary circuit.

In parallel with the primary of the transformer is a low voltage relay 35 which operate when the voltage drops to a predetermined value to close a circuit fromthe generator through the signal device 36 such as a bell or speaker. There is thus provided an audible signal in addition to the visual signal resulting from illumination of the glow tube 33 from the flow of current in the secondary circuit of the transformer.

In explaining the operation of the invention it is, of course, understood as already explained that the pipe I is grounded. This ground is usually provided by contact of the pipe with the earth in advance of the point where wrappin and coating are taking place. Hence the secondary circuit of the transformer is normally closed except for the insulating coating 2 about the pipe I and upon which it is intended the electrode 5 shall roll. The voltage supplied by the transformer will normally cause a slight flow of current comprising capacity, leakage and corona currents to cause the tube 33 to glow, if used. If, however, the electrode and pressure member 5 is moved to a position over a void in the coating 2, an arc will result and there will be an increased flow of current whereby the glow tube will be illuminated with a much greater brilliancy.

Preferably, however, the audible signal means 36 is relied upon. To this end desired voltage is applied and the relay is adjusted until it opcrates to close the circuit through the device 36. It is then slightly readjusted until the leakage, capacity and corona currents will not effect operation of the relay. If then, there is a void proximate the electrode 5, the additional arcing current will be sufilcient to cause closure of the relay whereby the audible signal will be given.

The electrode and pressure member 5 may be readily moved along the pipe I and coating 2 by means of the operator. Inasmuch as the coating 2 has not yet hardened the operator will cause movement of the electrode as indicated by the arrows I9 whereby there i effected a kneading action upon the coating. Such action will cause closure of the void or holiday, and a cessation of either the visual or audible signal will indicate when such closure is complete. The electrode and pressure member 5 can then be moved forward whereby productive action is had to detect and to eliminate voids within the coating 2 prior to the time such coating has hardened.

In Fig. 6 a slightly modified arrangement is shown where the coil sprin 5 is mounted upon a block having the brackets 4| for receiving the electrode spring 5 and a second spring 5' has also been shown as being spaced a short distance from the electrode spring 5". The handle 2| is connected to this block so that the apparatus may be moved along the pipe I after it has been coated and wrapped. As indicated by the arrow in Fig. 6 the apparatus will move to the right as illustrated so that the spring 5' will iron or knead the coating and wrapping prior to the testing thereof by means of the electrode spring 5". In this manner a double action is applied to the coating which has been found in actual practice to be very beneficial.

Referring again to Fig. 7 an arm or extension 42 beyond the wrapping machine portion of the apparatus has been shown and the handle 2! connected to the plug All and the electrode spring 5 and ironing spring 5 has been illustrated so that the ironing and testing for voids can be accomplished simultaneously with the coating and wrapping as a single operation.

Of course a suitable alarm or signal can be used as previously described and a separate or special operator need not be provided with this apparatus of Fig. 7.

Broadly the invention contemplates a means and method of applyin coating and wrapping material to pipe so as to eliminate the majority of the voids, bubbles, and wrinkles which may occur and to also test the coating and wrapping for voids.

The invention claimed is:

1. In an ironing device for the coating and wrapping being placed upon a pipe, a coiled spring encircling the coated and wrapped pipe, connections for the spring ends to maintain the spring under tension against the wrapping while the coating is still plastic, a handle for said spring to move the spring back and forth to knead and iron the coating and wrapping, and means comprising a filling material carried by said spring, and a lubricant upon the said sprin filling material so that coating material will not adhere to said spring.

2. A device for ironing and smoothing the wrapping material on a pipe surface which is applied with a heated plastic coating material while such plastic is still unhardened comprising, a coil spring held in tension about the pipe, the coating and the wrapping, a handle means connecting with said spring to move the spring to and fro along the pipe to iron the coating so as to knead out air spaces and spread the coating by the tension of the spring and such kneading, and an absorbent material in said spring, a lubricant on such material so that the coating material will not adhere to such spring.

ALONZO L. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,420,911 Davis et a1 June 27, 1922 1,427,817 Hutchinson Sept. 5, 1922 1,561,483 Pickard Nov. 17, 1925 1,950,484 Clarvoe Mar. 13, 1934 1,973,505 Rolfs et al Sept. 11, 1934 1,985,997 Keeran Jan. 1, 1935 2,043,528 Davis June 9, 1936 2,304,513 Stearns Dec. 8, 1942. 2,332,182 Stearns Oct. 19, 1943 2,445,808 Stenstrom July 27, 1948 FOREIGN PATENTS Number Country Date 260,997 Great Britain July 14, 1927 

